| 1. |
- Telloni, Daniele, et al.
(författare)
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Evolution of Solar Wind Turbulence from 0.1 to 1 au during the First Parker Solar Probe-Solar Orbiter Radial Alignment
- 2021
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8205 .- 2041-8213. ; 912:2
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Tidskriftsartikel (refereegranskat)abstract
- The first radial alignment between Parker Solar Probe and Solar Orbiter spacecraft is used to investigate the evolution of solar wind turbulence in the inner heliosphere. Assuming ballistic propagation, two 1.5 hr intervals are tentatively identified as providing measurements of the same plasma parcels traveling from 0.1 to 1 au. Using magnetic field measurements from both spacecraft, the properties of turbulence in the two intervals are assessed. Magnetic spectral density, flatness, and high-order moment scaling laws are calculated. The Hilbert-Huang transform is additionally used to mitigate short sample and poor stationarity effects. Results show that the plasma evolves from a highly Alfvenic, less-developed turbulence state near the Sun, to fully developed and intermittent turbulence at 1 au. These observations provide strong evidence for the radial evolution of solar wind turbulence.
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| 2. |
- Biancari, Fausto, et al.
(författare)
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Multicenter study on postcardiotomy venoarterial extracorporeal membrane oxygenation
- 2020
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Ingår i: Journal of Thoracic and Cardiovascular Surgery. - : Elsevier BV. - 0022-5223 .- 1097-685X. ; 159:5, s. 1844-1854
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The aim of this study was to identify the risk factors associated with early mortality after postcardiotomy venoarterial extracorporeal membrane oxygenation. Methods: This is an analysis of the postcardiotomy extracorporeal membrane oxygenation registry, a retrospective multicenter cohort study including 781 patients aged more than 18 years who required venoarterial extracorporeal membrane oxygenation for cardiopulmonary failure after cardiac surgery from 2010 to 2018 at 19 cardiac surgery centers. Results: After a mean venoarterial extracorporeal membrane oxygenation therapy of 6.9 ± 6.2 days, hospital and 1-year mortality were 64.4% and 67.2%, respectively. Hospital mortality after venoarterial extracorporeal membrane oxygenation therapy for more than 7 days was 60.5% (P = .105). Centers that had treated more than 50 patients with postcardiotomy venoarterial extracorporeal membrane oxygenation had a significantly lower hospital mortality than lower-volume centers (60.7% vs 70.7%, adjusted odds ratio, 0.58; 95% confidence interval, 0.41-0.82). The postcardiotomy extracorporeal membrane oxygenation score was derived by assigning a weighted integer to each independent pre–venoarterial extracorporeal membrane oxygenation predictors of hospital mortality as follows: female gender (1 point), advanced age (60-69 years, 2 points; ≥70 years, 4 points), prior cardiac surgery (1 point), arterial lactate 6.0 mmol/L or greater before venoarterial extracorporeal membrane oxygenation (2 points), aortic arch surgery (4 points), and preoperative stroke/unconsciousness (5 points). The hospital mortality rates according to the postcardiotomy extracorporeal membrane oxygenation score was 0 point, 45.6%; 1 point, 40.5%; 2 points, 51.1%; 3 points, 57.8%; 4 points, 70.7%; 5 points, 68.3%; 6 points, 77.5%; and 7 points or more, 89.7% (P < .0001). Conclusions: Age, female gender, prior cardiac surgery, preoperative acute neurologic events, aortic arch surgery, and increased arterial lactate were associated with increased risk of early mortality after postcardiotomy venoarterial extracorporeal membrane oxygenation. Center experience with postcardiotomy venoarterial extracorporeal membrane oxygenation may contribute to improved results.
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| 3. |
- Bruno, Roberto, et al.
(författare)
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Comparative Study of the Kinetic Properties of Proton and Alpha Beams in the Alfvénic Wind Observed by SWA-PAS On Board Solar Orbiter
- 2024
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 969:2
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Tidskriftsartikel (refereegranskat)abstract
- The problems of heating and acceleration of solar wind particles are of significant and enduring interest in astrophysics. The interactions between waves and particles are crucial in determining the distributions of proton and alpha particles, resulting in non-Maxwellian characteristics, including temperature anisotropies and particle beams. These processes can be better understood as long as the beam can be separated from the core for the two major components of the solar wind. We utilized an alternative numerical approach that leverages the clustering technique employed in machine learning to differentiate the primary populations within the velocity distribution rather than employing the conventional bi-Maxwellian fitting method. Separation of the core and beam revealed new features for protons and alphas. We estimated that the total temperature of the two beams was slightly higher than that of their respective cores, and the temperature anisotropy for the cores and beams was larger than 1. We concluded that the temperature ratio between alphas and protons largely over 4 is due to the presence of a massive alpha beam, which is approximately 50% of the alpha core. We provided evidence that the alpha core and beam populations are sensitive to Alfvénic fluctuations and the surfing effect found in the literature can be recovered only when considering the core and beam as a single population. Several similarities between proton and alpha beams would suggest a common and local generation mechanism not shared with the alpha core, which may not have necessarily been accelerated and heated locally.
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| 4. |
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| 5. |
- Sánchez-Cano, Beatriz, et al.
(författare)
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Solar Energetic Particle Events Detected in the Housekeeping Data of the European Space Agency's Spacecraft Flotilla in the Solar System
- 2023
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Ingår i: Space Weather. - : American Geophysical Union (AGU). - 1542-7390. ; 21:8
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Tidskriftsartikel (refereegranskat)abstract
- Despite the growing importance of planetary Space Weather forecasting and radiation protection for science and robotic exploration and the need for accurate Space Weather monitoring and predictions, only a limited number of spacecraft have dedicated instrumentation for this purpose. However, every spacecraft (planetary or astronomical) has hundreds of housekeeping sensors distributed across the spacecraft, some of which can be useful to detect radiation hazards produced by solar particle events. In particular, energetic particles that impact detectors and subsystems on a spacecraft can be identified by certain housekeeping sensors, such as the Error Detection and Correction (EDAC) memory counters, and their effects can be assessed. These counters typically have a sudden large increase in a short time in their error counts that generally match the arrival of energetic particles to the spacecraft. We investigate these engineering datasets for scientific purposes and perform a feasibility study of solar energetic particle event detections using EDAC counters from seven European Space Agency Solar System missions: Venus Express, Mars Express, ExoMars-Trace Gas Orbiter, Rosetta, BepiColombo, Solar Orbiter, and Gaia. Six cases studies, in which the same event was observed by different missions at different locations in the inner Solar System are analyzed. The results of this study show how engineering sensors, for example, EDAC counters, can be used to infer information about the solar particle environment at each spacecraft location. Therefore, we demonstrate the potential of the various EDAC to provide a network of solar particle detections at locations where no scientific observations of this kind are available.
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| 6. |
- Verscharen, Daniel, et al.
(författare)
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The angular-momentum flux in the solar wind observed during Solar Orbiter's first orbit
- 2021
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 656
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Tidskriftsartikel (refereegranskat)abstract
- Aims. We present the first measurements of the angular-momentum flux in the solar wind recorded by the Solar Orbiter spacecraft. Our aim is to validate these measurements to support future studies of the Sun's angular-momentum loss. Methods. We combined 60-min averages of the proton bulk moments and the magnetic field measured by the Solar Wind Analyser and the magnetometer onboard Solar Orbiter. We calculated the angular-momentum flux per solid-angle element using data from the first orbit of the mission's cruise phase in 2020. We separated the contributions from protons and from magnetic stresses to the total angular-momentum flux.Results. The angular-momentum flux varies significantly over time. The particle contribution typically dominates over the magnetic-field contribution during our measurement interval. The total angular-momentum flux shows the largest variation and is typically anti-correlated with the radial solar-wind speed. We identify a compression region, potentially associated with a co-rotating interaction region or a coronal mass ejection, which leads to a significant localised increase in the angular-momentum flux, albeit without a significant increase in the angular momentum per unit mass. We repeated our analysis using the density estimate from the Radio and Plasma Waves instrument. Using this independent method, we find a decrease in the peaks of positive angular-momentum flux, but otherwise, our results remain consistent.Conclusions. Our results largely agree with previous measurements of the solar wind's angular-momentum flux in terms of amplitude, variability, and dependence on radial solar-wind bulk speed. Our analysis highlights the potential for more detailed future studies of the solar wind's angular momentum and its other large-scale properties with data from Solar Orbiter. We emphasise the need for studying the radial evolution and latitudinal dependence of the angular-momentum flux in combination with data from Parker Solar Probe and other assets at heliocentric distances of 1 au and beyond.
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